I would highly advise you NOT to do this....the iPad 2 is not intended to be taken apart by average people (meaning only Apple is intended to using their tools). Furthermore, I get the thrill factor behind modifying certain hardware but DO NOT let that thrill go too far. The iPhone 4's camera will not fit in the iPad 2 due to space issues. Plus, you'd need to modify iPad's camera software to even take advantage of the iPhone 4 camera. To sum this all up: Don't bother doing this, it's not the worth the time or risk.
Geez, what a buzzkill you are, eh? Im guesssing you don't get invited to a lot of parties.
I have to ask though... on one hand you make comments such as "I wouldn't take the thrill that far" , and "only Apple has the necessary tools to take it apart" etc.. which tells us that in all actuality, you have no real idea as to whether or not it will work.
Point is, you shouldn't make qualifying statements as such, if you're not informed enough to do so. This also means providing proof to back up your claims since guessing isn't good enough.
I simply would advise not taking it apart unless you have the proper documentation and tools, and unless you're ready to run the possible risk of breaking something. But you're a big boy, and im sure you know this already. Plus hey... safe= zzzzzzzzzzzzzzzzzzzzzz
Doug